Adaptor for converting electrical two-receptacle sockets into threereceptacle sockets



390,358 RECEPTACLE SOCKETS INTO THREE-RECEPTACLE SOCKETS June 25, 1968 A. M. ARCHER ADAPTOR FOR CONVERTING ELECTRICAL TWO Filed June 30. 1966 INVENTOR ANDREW M. ARCHER United States Patent 3,390,368 ADAPTOR FOR CONVERTING ELECTRICAL TWO-RECEPTACLE SOCKETS INTO THREE- RECEPTACLE SOCKETS Andrew M. Archer, Rincon Seamans Unit,

San Francisco, Calif. 94119 Filed June 30, 1966, Ser. No. 561,901 8 Claims. (Cl. 339-14) ABSTRACT OF THE DISCLOSURE An adaptor for converting an electrical two-receptacle outlet socket into a threereceptacle outlet socket providing a ground connection, comprising a body of insulating material having a first, second, third and fourth receptacle provided at one side thereof, first and second conductive members in said first and second receptacle, respectively, and connector blades in conductive contact with said first and second conductive members projecting from another side of said body, a third conductive member extending from said third to said fourth receptacle, said third conductive member having an eyelet within said fourth receptacle, a bolt engaged within said eyelet and having a head within said fourth receptacle and a flange firmly secured to said bolt above said eyelet within said fourth receptacle, said bolt having a threaded end protruding from said body on said other side thereof. Anchoring members may be provided on said connector blades.

The present invention relates to electrical outlet sockets. In the past, most electrical appliances had only two wires which delivered the electrical current to the appliance and which were provided with plugs having two connector prongs or blades. Accordingly, most of the electrical outlet sockets installed in public and private buildings provide only two slots or receptacles into which the two blades or prongs of the plug are inserted and wherein they make contact with conductive members that are connected to a distant source of electric power. For reasons of safety there has been an increasing demand to provide a separate ground connection for every appliance and accordingly their plugs have three prongs or blades, two for supplying the electrical current to the appliance and one for connecting its frame to ground. At the moment the trend is such that soon all new electrical appliances will be provided wtih three-pronged connector plugs, and in fact safety regulations may soon make such three-pronged plugs mandatory. It becomes, therefore, increasingly necessary to replace the two-receptacle sockets in public and private buildings by three-receptacle sockets to be able to use newly purchased appliances. Such an installation requires skilled labor and is therefore costly.

It is an object of the present invention to provide an adaptor for converting a two-receptacle outlet socket into a three-receptacle outlet socket, i.e. a connector socket that possesses a receptacle for establishing a ground connection apart from the current supply outlet slots.

More particularly it is an object of the invention to provide an adaptor, of the type referred to, that is inexpensive and may readily and without danger be installed by an inexperienced person.

Still another object of the invention is to provide an adaptor, of the type referred to, that once installed remains permanently in position and cannot accidentally be disconnected.

These and other objects of the present invention will be apparent from the following description of the accompanying drawing which illustrate a preferred embodiment thereof and wherein 3,390,368 Patented June 25, 1968 FIGURE 1 is a front elevation of an adaptor embodymg my invention;

FIGURE 2 is a section through the adaptor shown in FIGURE 1 and the outlet socket behind the adaptor, taken along line 22 of FIGURE 1 and viewed in the direction of the arrows associated with the line;

FIGURE 3 is another section through the adaptor and the original socket taken along line 33 of FIGURE 1; and

FIGURE 4 is a fragmentary perspective of certain components of the adaptor.

Most of the sockets at present installed in buildings are twin sockets, i.e. they provide juxtaposed outlets for two plugs and the exemplary embodiment of the invention illustrated in the accompanying drawing is therefore constructed to convert such a twin socket of conventional design, into a twin socket wherein a third receptacle designed to establish a ground connection, is associated with each pair of slots that provide connections to the source of electrical power. Having reference to the accompanying drawing, the adaptor of the invention comprises a housing 10 in the form of a rectangular block of insulating material which is to serve as the socket for two threebladed plugs and has accordingly two pairs of slot-shaped receptacles 12a, 14a and 12b, 14b that may be located near the opposite ends of its top surface 11 at opposite sides of its longitudinal plane of symmetry xx, and twotunnel-shaped receptacles 15a and 15b that may be located in and about said plane of symmetry in areas somewhat closer to the center of the housing than the slots 12 and 14. Arranged in the center of the housing 10 is a fourth type of receptacle 16 which is of cylindrical shape and is of a larger size than the other receptacles. The block 10 is mounted upon a panel 18 of insulating material that is intended to take the place of the panel which is usually provided in sockets of conventional design to cover the recess in the wall, in which the framework of the sockets is located. Arranged in each of the slots 12 and 14 adjacent one of their side walls is a conductive contact element of conventional design, usually a spring member such as shown at 20, and secured to the opposite wall of each slot may be a rounded head 22 to cam an inserted contact blade, such as indicated at 24 in phantom lines in FIGURE 3, reliably into conductive contact with the spring member 20.

Conductively connected to each spring member 20, or forming an integral part thereof, is a contact blade or prong 26 which projects from the bottom surface of the housing 10 and protrudes through a suitable aperture 28 in the panel 18. Hence, two pairs of contact blades or prongs 26, one pair for each pair of outlet slots 12, 14, project from the bottom of the panel 18. Each of the tunnel-shaped receptacles 15 in the housing 10' is provided with a contact member 300 or 30b, respectively, located adjacent one of its sides (FIGURE 2) to make conductive contact with the ground connector prong indicated in phantom lines at 32, of the three-prong appliance plug 31 (FIGURE 2). Arranged in a recess at the bottom of the housing 10 is a strip of metal 38 which traverses the bottom of the centrally located cylindrical receptacle 16 and has its opposite ends conductively connected to the contact members 3012 and 30b in the two tunnel-shaped receptacles 15a and 15b, respectively. In accordance with the invention the center area of said strip 38 which is located at the bottom of the cylindrical receptacle 16 and is exposed by said receptacle for access from the outside, is employed to do both, provide a permanent attachment of the adaptor to the frame of the conventional socket which is to be converted into a three-outlet socket, and to establish a permanent ground connection for the spring contacts 30a and 30b in both the tunnel-shaped receptacles 15a and 15b.

The hereinbefore mentioned cover panels of conventional twin-outlet sockets are usually held in position by a headed screw that passes through a centrally located aperture in said panel and engages a threaded aperture 37 in the frame 39 the socket which is always grounded, such as by means of lateral brackets 40a and 40b that are attached to the wall (FIGURES 2- and 4).

In accordance with the invention the area of the strip 38 which is exposed at the bottom of the cylindrical receptacle 16 forms an eyelet or grommet 42. Said eyelet is engaged by the threaded end 44 of a screw bolt 45 whose head 46 is located in the cylindrical receptacle 16 and Which carries firmly secured thereto an annular flange 48 that is located above the eyelet 42.

When a conventional twin socket is to be converted by the adaptor of the invention into a socket providing ground outlets in addition to the current carrying outlets, the first thing to do is to remove its cover panel. This is accomplished by Withdrawing the hereinbefore mentioned screw by means of which the panel is secured to the frame of the socket. All that is then necessary is to plug the four flat blades or prongs 26 of the adaptor into the twin slots of the original socket. This does not only place the four blades of the adaptor into conductive contact with the current carrying contact members 47 of said original socket (FIGURES 2 and 3), it also aligns the eyelet 42 in the conductive strip 38 of the adaptor and the threaded end of the screw bolt 45 within said eyelet with the threaded aperture 37 in the frame 39 of the original socket. Now it is merely necessary to engage the threaded end 44 of the bolt 45 in the aperture 37 and turn it in the proper manner until the resultant descent of the bolt 45 into said aperture brings the annular flange 48 of the bolt to bear upon the strip 38. This establishes dependably conductive contact between the strip 38, the bolt 45 and the grounded frame 39 of the original socket. When the screw bolt 45 has been properly tightened, and the adaptor is thus firmly secured to the frame of the original socket, the converted socket is ready for use.

To facilitate the described installation procedure and to make it impossible for the adaptor to become accidentally detached from the original socket, I provide adjacent the protruding blades 26 of the adaptor of my invention anchoring members 50 that may be inserted into the contact slots of the original socket together with the contact blades of the adaptor and once inserted, lock the adaptor permanently to the original socket. Having reference to FIGURE 2, each of the contact blades 26 of the adaptor carries adjacent the outer one of its flat surfaces and directly below the level of the panel 18 a strip of a resiliently yieldable material whose lower end is sharply bent backwardly and outwardly away from the connector blades, with its backwardly folded end portion 52 extending normally at an acute angle thereto. Said strip may either be held embedded in the housing 10 adjacent the contact prong 26 or may be soldered to the outer surface of the prong itself. When the contact blades 26 of the adaptor are inserted into the slots of the original socket, and the sharply folded ends of the strips 50 come against and enter the slots in the socket, their outwardly bent end portions 52 yield backwardly into positions parallel to the contact blades. In this position they readily enter the slots of the original socket together with the contact blades 26-. However, once the free extremities of said end portions 52 descend below the lips 54 formed by the casing of the original socket adjacent the slots of said sockets, said bent end portions 52 return to their initial tilted positions due to the resiliency of the material from which they are made. Thus, they hook underneath said lips 54 in the manner of a barb resisting positively any effort to detach the adaptor from the original socket. It is now an easy matter for even an unskilled layman to thread the screw bolt 45 into the aperture 37 in the frame 39 of the original socket and establish a dependable ground connection for the two tunnel-shaped slots 15a and 15b of the adaptor, as described hereinbefore.

It remains to be pointed out that for reasons of safety I prefer the head 46 of the screw bolt 45 to be of the type that requires a wrench or a pair of pliers rather than a screw driver for manipulation, and I have therefore shown it to be polygonal (FIGURE 4). This precludes the dangerous possibility that in an effort to secure the adaptor in its proper position to the original socket an inexperienced person with poor eyesight may insert a screw driver accidentally into one of the current carrying outlet slots and come to harm.

While I have explained my invention with the aid of an exemplary embodiment thereof, the invention is not limited to the constructional details shown and described by way of example, which may be departed from without departing from the scope and spirit of the invention.

I claim:

1. An adaptor for converting a two-receptacle electrical outlet socket into a three-receptacle socket providing a ground connection comprising a body of insulating material having three receptacles on one side thereof each containing a conductive contact member, a pair of contact blades in conductive connection with the contact members of two of said receptacles arranged to project from another side of said body of insulating material, a member of conductive material in conductive connection with the conductive contact member of the third of said receptacles, said member being arranged to form an eyelet, and a headed screw bolt engaged in said eyelet and having an annular flange above said eyelet.

2. An adaptor according to claim 1 including anchoring members adjacent said contact blades.

3. An adaptor for converting a two-receptacle electrical outlet socket into a three-receptacle outlet socket providing a ground connection comprising a body of insulating material having a first, second, third and fourth receptacle provided at one side thereof, first and second conductive members in said first and second receptacles and connector blades projecting from another side of said body in conductive contact with said conductive members, a third conductive member extending from said third to said fourth receptacle and arranged to form an eyelet within said fourth receptacle, a bolt engaged in said eyelet and having a head within said fourth receptacle, a flange firmly secured thereto above said eyelet within said fourth receptacle and a threaded end protruding from said body on said other side thereof.

4. An adaptor according to claim 3 wherein said body of insulating material is mounted upon a cover panel.

5. An adaptor according to claim 3 wherein said first and second receptacles are slot-shaped, said third receptacle is tunnel-shaped and said fourth receptacle is of cylindrical shape.

6. An adaptor according to claim 3 wherein the head of said screw bolt is of polygonal contour.

7. An adaptor according to claim 3 including anchoring members adjacent said contact blades.

8. An adaptor according to claim 7 wherein said anchoring members are strips of a resiliently yieldable material and have end portions folded sharply backwardly and away from said blades so as to define an acute angle with said blades.

References Cited UNITED STATES PATENTS 1,677,269 7/1928 Burghart -9 XR 1,950,920 3/1934 Gora 83-469 2,498,743 2/ 1950 Theriault 339-91 XR 3,131,013 4/1964 Carlson 339-14 MARVIN A, CHAMPION, Primary Examiner. P. A. CLIFFORD, Examiner. 

